Geotechnical analyses were carried out to examine the contributions of engineering geological properties of subgrade soils to the failure of the Akure-Ikere Ekiti road,Southwestern Nigeria.Field observations revealed ...Geotechnical analyses were carried out to examine the contributions of engineering geological properties of subgrade soils to the failure of the Akure-Ikere Ekiti road,Southwestern Nigeria.Field observations revealed that the road is in a very poor state of serious deformation and disrepair as most parts of the road alignment have failed.The alignment of the studied road is predominantly underlain by Granite,Charnockites,and Migmatites.Laboratory tests results showed that the natural moisture content ranges from 10.98 to 21.4%,liquid limit from 22.8 to 47.7%,plastic limit from 19.2 to 24.6,plasticity index 3.6 to 26.3%.The grain size analysis revealed that the amount of fines ranges from 15.9 to 49%.Others are linear shrinkage,between 1.4 and 10%,free swell between 25 and 46%,maximum dry density from 1593 to 2016 kg/m,and CBR between 5 and 48%.The specific gravity ranges from 2.64 to 2.74.With reference to AASHTO classification,5% of the samples was classified as A-4,15% classified as A-2-4,40% classified as A-6,while 40% classified as A-7-6.The dominance of fair-to-good California bearing ratio,fair to good maximum dry density,high linear shrinkage and A-7-6,A-6,and A-2-4 soil groups have combined to give fair-to-good geotechnical properties to the studied soils.Generally,the fair to good geotechnical properties of soil of the road under study is an indication that the contribution of subgrade soil to the failure of the highway is negligible.The total breakdown of the road can be traced to substandard engineering specifications which are complemented by a poor drainage system.展开更多
This study focuses on the deformation characteristics of Kadui-2 Landslide by the influence of reservoir filling-drawdown and precipitation.A three-year monitoring project was implemented in order to observe the short...This study focuses on the deformation characteristics of Kadui-2 Landslide by the influence of reservoir filling-drawdown and precipitation.A three-year monitoring project was implemented in order to observe the short/long-term deformation.The slide mass experienced consistent deformation with a maximum cumulative displacement of 331.34 cm.Based on the recorded data of reservoir water level and precipitation during this period,a two-dimensional(2-D)finite element model using Geostudio software was set up for deformation simulation under different conditions to understand the real influence of these triggering factors on landslide.The numerical simulation results are in consistent with monitoring field data.Both numerical simulation and field monitoring results exhibit that the maximum deformation occurred at the foreside of slumping mass.The slip surface shows significant creep characteristics decreasing as long-term shear strength reducing gradually.Reservoir water level fluctuation is the primary triggering factor to reactivate the landslide mass and has a negative correlation with deformation rate.Displacement rate increases with the reservoir drawdown and decreases with impoundment rise.Compared with reservoir filling-drawdown operation,rainfall has no significant effect on the slide motion of landslide due to limited penetration from the ground surface.展开更多
This study is aimed at developing statistical equations to estimate the inelastic displacement ratio of singledegree-of-freedom systems subjected to far fault repeated earthquakes. In the study, peak ground motion par...This study is aimed at developing statistical equations to estimate the inelastic displacement ratio of singledegree-of-freedom systems subjected to far fault repeated earthquakes. In the study, peak ground motion parameters are used to define the scatter of the original data. The ratio of peak ground acceleration to peak ground velocity, and peak ground velocity of the ground motion records and structural parameters such as period of vibration and lateral strength ratio are used in the proposed equations. For the development of the equations, nonlinear time history analyses of single-degree-offreedom systems are conducted. Then, the results are used in a multivariate regression procedure. The equations are verified by comparing the estimated results with the calculated results. The average error and coefficient of variation of the proposed equations are presented. The analyses results revealed that the direct use of peak ground motion parameters for the estimation of inelastic displacement ratio significantly reduced the scatter in the original data and yielded accurate results. From the comparative results it is also observed that results obtained using equations specific to peak ground velocity or peak ground acceleration to peak ground velocity ratio are similar.展开更多
According to empirical evidence,high levels of energy and considerable amounts of natural resources are used in the production of concrete.Given the context,this study explores self-consolidating concrete(SCC)that inc...According to empirical evidence,high levels of energy and considerable amounts of natural resources are used in the production of concrete.Given the context,this study explores self-consolidating concrete(SCC)that includes rice husk ash(RHA)and metal furnace slag(MFS)as an alternative to cement and the natural aggregates in standard SCC mixes.In this study,mixture designs are investigated with 20 wt.%of RHA,10–30 wt.%of MFS and water-to-powder material ratios of 0.30 and 0.40.Based on the findings regarding the fresh-state,hardened-state,and durability properties of the resulting SCC mixes,it is evident that the use of RHA and MFS can significantly improve the properties of concrete.The highest compressive strength was achieved for SCC with 20 wt.%RHA and 10 wt.%MFS.This outcome should be used as a basis for further investigations into the production of concrete materials that are both high-performance and sustainable.展开更多
This paper focuses on investigating the tendency of farmers in the greater area of Peloponnese as well as those on the greater area of Thessaly to participate in a program of environmental agricultural waste managemen...This paper focuses on investigating the tendency of farmers in the greater area of Peloponnese as well as those on the greater area of Thessaly to participate in a program of environmental agricultural waste management.The aim of the present study is to investigate the level of amount WTA(Willingness to Accept)against which the farmers would be willing to allow anyone to gather and carry away the leftovers of their farming exploitation.To serve the above goals,the agricultural leftovers are evaluated by the CVM(Contingent Valuation Method)as an environmental non-market economic commodity.The specimen response on utilization of the rejected biomass was satisfactory,since a good percentage of the interviewees are willing to contribute to this procedure for a minimal of remuneration,although investigations of this type are novel for Greek reality.From this investigation,it is perceived by the society the importance of alternative utilization of the rejected biomass.It is concluded that the minimum amount each interviewee is willing to accept as minimal remuneration and is affected by the way these biomass leftovers are managed,the age of the interviewees and the area in which they live.Those interviewees who use such biomass leftovers in alternative applications wish to be remunerated higher compared to those who relinquish such leftovers.The ordinal logistic model is listed in a broader category of generalized linear models for arrangement data.展开更多
This paper presents some recent developments in modelling and numerical analysis of piezoelectric systems and controlled smart structures based on a ?nite element formulation with embedded control. The control aims at...This paper presents some recent developments in modelling and numerical analysis of piezoelectric systems and controlled smart structures based on a ?nite element formulation with embedded control. The control aims at vibration suppression of the structure subjected to external disturbances, like wind and noise, under the presence of model inaccuracies, using the available measurements and controls. A smart structure under dynamic loads is analysed and comparison between results for beam with and without control is made. The numerical results show that the control strategy is very effective and suppresses the vibrations of the structure.展开更多
Hydrochemical facies, groundwater evolution, and physicochemical reactions between soil or rock and water are of considerable importance when evaluating or predicting the nature of anthropogenic impacts on groundwater...Hydrochemical facies, groundwater evolution, and physicochemical reactions between soil or rock and water are of considerable importance when evaluating or predicting the nature of anthropogenic impacts on groundwater quality. In this respect a total of 67 ground water samples were collected randomly in Akure, southwestern, Nigeria from hand pump/dug wells and analyzed for major cations and anions. The domination of cations and anions was in the order of Ca2+ > K+ > Na+ > Mg2+ and ?> Cl- > ?> ?respectively. The pH and Eh of the water samples show an acidic condition, with low salinity hazard (generally less than 250 μS/cm). The Piper classification for hydrogeochemical facies indicates carbonate hardness (secondary alkalinity) exceeds 50% that is by alkaline earths and weak acids, with Ca2+ + Mg2+ + ?water-type. This also suggests a meteoric origin of water quality caused by rock-water interaction. The ratio of ?and Cl- is greater than 1 and implies recharge area or upper water flow course of carbonate rocks (interaction of water with aquifer material). The Na+:Cl- is less than 0.7 signifying loss of Na+ through precipitation of evaporating water;the water is Ca2+ rich and Na+ depleted with Mg2+:Ca2+ less than 0.5 and Na+:K+ less than 15. The Na+:Ca2+ (<1) indicates reverse ionic exchange. The Ca2+:?+ ?for the samples is less than 1.0 suggestive of flow of water through the normal hydrological cycle. The calculated range of values of sodium absorption ratio (1.89 - 26.42), permeability index (42.67 - 170.24), residue sodium carbonate (-1 to 5), magnesium ratio (4 - 53), Kelly ratio (0.04 - 0.84), percent sodium (0.41 - 3.45) suggest good water suitable for irrigation purposes. In addition, the Wilcox plot shows that 98% of the water samples belong to “good to permissible category” for irrigation use.展开更多
Recently, many important nonlinear partial differential equations arising in the applied physical and mathematical sciences have been tackled by a popular approach, the so-called Exp-function method. In this paper, we...Recently, many important nonlinear partial differential equations arising in the applied physical and mathematical sciences have been tackled by a popular approach, the so-called Exp-function method. In this paper, we present some shortcomings of this method by analyzing the results of recently published papers. We also discuss the possible improvement of the effectiveness of the method.展开更多
A relational matching approach for imagery-to-GIS data is presented. This method applies image aspect interpretation and geospatial data mining techniques to realize their integration. Three-dimensional （3D） primiti...A relational matching approach for imagery-to-GIS data is presented. This method applies image aspect interpretation and geospatial data mining techniques to realize their integration. Three-dimensional （3D） primitives, standing for houses, are chosen and their projections are represented by these aspects. The hierarchy aspect graphs are constructed to represent their intercon- nected relations. In this connection arcs are described by attribute data via formulated coding regulations. The nodes of the graph represent image features and their attributes can contain measurements on these features. The arcs of the graph represent relations between features and their attributes can contain measurements on spatial relations. Data mining is used to discover the semantic relationship of these primitives. Aerial images are interpreted via these aspects and geospatial data mining. Our experimental results demonstrate that the method oresented is cat）able of effectively interoreting aerial images and extracting high accuracv from the DBM （digital building model） at a rate of 87%.展开更多
High early strength(HES)concrete pavements are commonly opened to traffic within the first 24 h after construction,making early-opening decisions critical for pavement quality and traffic operations.Currently,most sta...High early strength(HES)concrete pavements are commonly opened to traffic within the first 24 h after construction,making early-opening decisions critical for pavement quality and traffic operations.Currently,most state departments of transportation rely on compressive strength testing for early-opening decision making.However,there laboratory tests are labor intensive,costly and not always representative of field strength development.In this study,non-destructive testing(maturity and ultrasonic tomography)was explored for faster and reliable in-situ strength estimations.An experimental section constructed using HES concrete was routinely monitored using compressive testing,maturity,and ultrasonic tomography in the first 24 h after construction.The shear wave velocity,measured using ultrasonic tomography,was able to capture the strength-gain variability within a single slab and between different slabs due to the ability to monitor several locations in a short period of time.Maturity results were consistently conservative in the first 24 h of monitoring.Results show that both maturity testing and ultrasonic tomography are able to replace or add to conventional strength testing for HES concrete pavements to facilitate making the opening decision within the first 24 h.Ultrasonic tomography proved more beneficial as a result of the device's portability,increased speed of testing,and accurate estimations of HES concrete strength for the entire pavement length.展开更多
As college campuses reopened in fall 2020,we saw a large-scale experiment unfold on the efficacy of various strategies to contain the SARS-CoV-2 virus.Traditional individual surveillance testing via nasal swabs and/or...As college campuses reopened in fall 2020,we saw a large-scale experiment unfold on the efficacy of various strategies to contain the SARS-CoV-2 virus.Traditional individual surveillance testing via nasal swabs and/or saliva is among the measures that colleges are pursuing to reduce the spread of the virus on campus.Additionally,some colleges are testing wastewater on their campuses for signs of infection,which can provide an early warning signal for campuses to locate COVID-positive individuals.However,a representation of wastewater surveillance has not yet been incorporated into epidemiological models for college campuses,nor has the efficacy of wastewater screening been evaluated relative to traditional individual surveillance testing,within the structure of these models.Here,we implement a new model component for wastewater surveillance within an established epidemiological model for college campuses.We use a hypothetical residential university to evaluate the efficacy of wastewater surveillance for maintaining low infection rates.We find that wastewater sampling with a 1-day lag to initiate individual screening tests,plus completing the subsequent tests within a 4-day period can keep overall infections within 5%of the infection rates seen with traditional individual surveillance testing.Our results also indicate that wastewater surveillance can effectively reduce the number of false positive cases by identifying subpopulations for surveillance testing where infectious individuals are more likely to be found.Through a Monte Carlo risk analysis,we find that surveillance testing that relies solely on wastewater sampling can be fragile against scenarios with high viral reproductive numbers and high rates of infection of campus community members by outside sources.These results point to the practical importance of additional surveillance measures to limit the spread of the virus on campus and the necessity of a proactive response to the initial signs of outbreak.展开更多
文摘Geotechnical analyses were carried out to examine the contributions of engineering geological properties of subgrade soils to the failure of the Akure-Ikere Ekiti road,Southwestern Nigeria.Field observations revealed that the road is in a very poor state of serious deformation and disrepair as most parts of the road alignment have failed.The alignment of the studied road is predominantly underlain by Granite,Charnockites,and Migmatites.Laboratory tests results showed that the natural moisture content ranges from 10.98 to 21.4%,liquid limit from 22.8 to 47.7%,plastic limit from 19.2 to 24.6,plasticity index 3.6 to 26.3%.The grain size analysis revealed that the amount of fines ranges from 15.9 to 49%.Others are linear shrinkage,between 1.4 and 10%,free swell between 25 and 46%,maximum dry density from 1593 to 2016 kg/m,and CBR between 5 and 48%.The specific gravity ranges from 2.64 to 2.74.With reference to AASHTO classification,5% of the samples was classified as A-4,15% classified as A-2-4,40% classified as A-6,while 40% classified as A-7-6.The dominance of fair-to-good California bearing ratio,fair to good maximum dry density,high linear shrinkage and A-7-6,A-6,and A-2-4 soil groups have combined to give fair-to-good geotechnical properties to the studied soils.Generally,the fair to good geotechnical properties of soil of the road under study is an indication that the contribution of subgrade soil to the failure of the highway is negligible.The total breakdown of the road can be traced to substandard engineering specifications which are complemented by a poor drainage system.
基金supported by to the National Key Research and Development Program of China(No.2018YFC1505401)。
文摘This study focuses on the deformation characteristics of Kadui-2 Landslide by the influence of reservoir filling-drawdown and precipitation.A three-year monitoring project was implemented in order to observe the short/long-term deformation.The slide mass experienced consistent deformation with a maximum cumulative displacement of 331.34 cm.Based on the recorded data of reservoir water level and precipitation during this period,a two-dimensional(2-D)finite element model using Geostudio software was set up for deformation simulation under different conditions to understand the real influence of these triggering factors on landslide.The numerical simulation results are in consistent with monitoring field data.Both numerical simulation and field monitoring results exhibit that the maximum deformation occurred at the foreside of slumping mass.The slip surface shows significant creep characteristics decreasing as long-term shear strength reducing gradually.Reservoir water level fluctuation is the primary triggering factor to reactivate the landslide mass and has a negative correlation with deformation rate.Displacement rate increases with the reservoir drawdown and decreases with impoundment rise.Compared with reservoir filling-drawdown operation,rainfall has no significant effect on the slide motion of landslide due to limited penetration from the ground surface.
文摘This study is aimed at developing statistical equations to estimate the inelastic displacement ratio of singledegree-of-freedom systems subjected to far fault repeated earthquakes. In the study, peak ground motion parameters are used to define the scatter of the original data. The ratio of peak ground acceleration to peak ground velocity, and peak ground velocity of the ground motion records and structural parameters such as period of vibration and lateral strength ratio are used in the proposed equations. For the development of the equations, nonlinear time history analyses of single-degree-offreedom systems are conducted. Then, the results are used in a multivariate regression procedure. The equations are verified by comparing the estimated results with the calculated results. The average error and coefficient of variation of the proposed equations are presented. The analyses results revealed that the direct use of peak ground motion parameters for the estimation of inelastic displacement ratio significantly reduced the scatter in the original data and yielded accurate results. From the comparative results it is also observed that results obtained using equations specific to peak ground velocity or peak ground acceleration to peak ground velocity ratio are similar.
基金funded by Faculty of Engineering,King Mongkut’s University of Technology North Bangkok,Contact No.ENG-62-48funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No.777823.
文摘According to empirical evidence,high levels of energy and considerable amounts of natural resources are used in the production of concrete.Given the context,this study explores self-consolidating concrete(SCC)that includes rice husk ash(RHA)and metal furnace slag(MFS)as an alternative to cement and the natural aggregates in standard SCC mixes.In this study,mixture designs are investigated with 20 wt.%of RHA,10–30 wt.%of MFS and water-to-powder material ratios of 0.30 and 0.40.Based on the findings regarding the fresh-state,hardened-state,and durability properties of the resulting SCC mixes,it is evident that the use of RHA and MFS can significantly improve the properties of concrete.The highest compressive strength was achieved for SCC with 20 wt.%RHA and 10 wt.%MFS.This outcome should be used as a basis for further investigations into the production of concrete materials that are both high-performance and sustainable.
文摘This paper focuses on investigating the tendency of farmers in the greater area of Peloponnese as well as those on the greater area of Thessaly to participate in a program of environmental agricultural waste management.The aim of the present study is to investigate the level of amount WTA(Willingness to Accept)against which the farmers would be willing to allow anyone to gather and carry away the leftovers of their farming exploitation.To serve the above goals,the agricultural leftovers are evaluated by the CVM(Contingent Valuation Method)as an environmental non-market economic commodity.The specimen response on utilization of the rejected biomass was satisfactory,since a good percentage of the interviewees are willing to contribute to this procedure for a minimal of remuneration,although investigations of this type are novel for Greek reality.From this investigation,it is perceived by the society the importance of alternative utilization of the rejected biomass.It is concluded that the minimum amount each interviewee is willing to accept as minimal remuneration and is affected by the way these biomass leftovers are managed,the age of the interviewees and the area in which they live.Those interviewees who use such biomass leftovers in alternative applications wish to be remunerated higher compared to those who relinquish such leftovers.The ordinal logistic model is listed in a broader category of generalized linear models for arrangement data.
文摘This paper presents some recent developments in modelling and numerical analysis of piezoelectric systems and controlled smart structures based on a ?nite element formulation with embedded control. The control aims at vibration suppression of the structure subjected to external disturbances, like wind and noise, under the presence of model inaccuracies, using the available measurements and controls. A smart structure under dynamic loads is analysed and comparison between results for beam with and without control is made. The numerical results show that the control strategy is very effective and suppresses the vibrations of the structure.
文摘Hydrochemical facies, groundwater evolution, and physicochemical reactions between soil or rock and water are of considerable importance when evaluating or predicting the nature of anthropogenic impacts on groundwater quality. In this respect a total of 67 ground water samples were collected randomly in Akure, southwestern, Nigeria from hand pump/dug wells and analyzed for major cations and anions. The domination of cations and anions was in the order of Ca2+ > K+ > Na+ > Mg2+ and ?> Cl- > ?> ?respectively. The pH and Eh of the water samples show an acidic condition, with low salinity hazard (generally less than 250 μS/cm). The Piper classification for hydrogeochemical facies indicates carbonate hardness (secondary alkalinity) exceeds 50% that is by alkaline earths and weak acids, with Ca2+ + Mg2+ + ?water-type. This also suggests a meteoric origin of water quality caused by rock-water interaction. The ratio of ?and Cl- is greater than 1 and implies recharge area or upper water flow course of carbonate rocks (interaction of water with aquifer material). The Na+:Cl- is less than 0.7 signifying loss of Na+ through precipitation of evaporating water;the water is Ca2+ rich and Na+ depleted with Mg2+:Ca2+ less than 0.5 and Na+:K+ less than 15. The Na+:Ca2+ (<1) indicates reverse ionic exchange. The Ca2+:?+ ?for the samples is less than 1.0 suggestive of flow of water through the normal hydrological cycle. The calculated range of values of sodium absorption ratio (1.89 - 26.42), permeability index (42.67 - 170.24), residue sodium carbonate (-1 to 5), magnesium ratio (4 - 53), Kelly ratio (0.04 - 0.84), percent sodium (0.41 - 3.45) suggest good water suitable for irrigation purposes. In addition, the Wilcox plot shows that 98% of the water samples belong to “good to permissible category” for irrigation use.
文摘Recently, many important nonlinear partial differential equations arising in the applied physical and mathematical sciences have been tackled by a popular approach, the so-called Exp-function method. In this paper, we present some shortcomings of this method by analyzing the results of recently published papers. We also discuss the possible improvement of the effectiveness of the method.
基金Projects 40574008 supported by the National Natural Science Foundation of China0131893 by the US National Science Foundation
文摘A relational matching approach for imagery-to-GIS data is presented. This method applies image aspect interpretation and geospatial data mining techniques to realize their integration. Three-dimensional （3D） primitives, standing for houses, are chosen and their projections are represented by these aspects. The hierarchy aspect graphs are constructed to represent their intercon- nected relations. In this connection arcs are described by attribute data via formulated coding regulations. The nodes of the graph represent image features and their attributes can contain measurements on these features. The arcs of the graph represent relations between features and their attributes can contain measurements on spatial relations. Data mining is used to discover the semantic relationship of these primitives. Aerial images are interpreted via these aspects and geospatial data mining. Our experimental results demonstrate that the method oresented is cat）able of effectively interoreting aerial images and extracting high accuracv from the DBM （digital building model） at a rate of 87%.
基金supported by the by the University of Pittsburgh Center for Impactful Resilient Infrastructure Science and Engineering(IRISE)the University of Pittsburgh Anthony Gill Chair。
文摘High early strength(HES)concrete pavements are commonly opened to traffic within the first 24 h after construction,making early-opening decisions critical for pavement quality and traffic operations.Currently,most state departments of transportation rely on compressive strength testing for early-opening decision making.However,there laboratory tests are labor intensive,costly and not always representative of field strength development.In this study,non-destructive testing(maturity and ultrasonic tomography)was explored for faster and reliable in-situ strength estimations.An experimental section constructed using HES concrete was routinely monitored using compressive testing,maturity,and ultrasonic tomography in the first 24 h after construction.The shear wave velocity,measured using ultrasonic tomography,was able to capture the strength-gain variability within a single slab and between different slabs due to the ability to monitor several locations in a short period of time.Maturity results were consistently conservative in the first 24 h of monitoring.Results show that both maturity testing and ultrasonic tomography are able to replace or add to conventional strength testing for HES concrete pavements to facilitate making the opening decision within the first 24 h.Ultrasonic tomography proved more beneficial as a result of the device's portability,increased speed of testing,and accurate estimations of HES concrete strength for the entire pavement length.
文摘As college campuses reopened in fall 2020,we saw a large-scale experiment unfold on the efficacy of various strategies to contain the SARS-CoV-2 virus.Traditional individual surveillance testing via nasal swabs and/or saliva is among the measures that colleges are pursuing to reduce the spread of the virus on campus.Additionally,some colleges are testing wastewater on their campuses for signs of infection,which can provide an early warning signal for campuses to locate COVID-positive individuals.However,a representation of wastewater surveillance has not yet been incorporated into epidemiological models for college campuses,nor has the efficacy of wastewater screening been evaluated relative to traditional individual surveillance testing,within the structure of these models.Here,we implement a new model component for wastewater surveillance within an established epidemiological model for college campuses.We use a hypothetical residential university to evaluate the efficacy of wastewater surveillance for maintaining low infection rates.We find that wastewater sampling with a 1-day lag to initiate individual screening tests,plus completing the subsequent tests within a 4-day period can keep overall infections within 5%of the infection rates seen with traditional individual surveillance testing.Our results also indicate that wastewater surveillance can effectively reduce the number of false positive cases by identifying subpopulations for surveillance testing where infectious individuals are more likely to be found.Through a Monte Carlo risk analysis,we find that surveillance testing that relies solely on wastewater sampling can be fragile against scenarios with high viral reproductive numbers and high rates of infection of campus community members by outside sources.These results point to the practical importance of additional surveillance measures to limit the spread of the virus on campus and the necessity of a proactive response to the initial signs of outbreak.
